Annual Planning Review
The Annual Planning Review (APR) represents a 20-year plan for the development of the electricity transmission network in South Australia, and forms a key input to the Annual Planning Report produced by the Electricity Supply Industry Planning Council (ESIPC).
Download 2009 Annual Planning Review [pdf]
Heywood Interconnector Export Capability
The South Australia to Victoria export capability on the Heywood interconnector has historically been capped at 300 MW under system normal conditions. This ceiling was established due to protection setting limitations and dynamic system stability considerations.
As advised in its Annual Planning Review published in May 2009, ElectraNet has undertaken an extensive review of the limitations impacting on South Australia’s export capability in accordance with clauses 5.2.3 and 5.6.2 of the National Electricity Rules. This review was undertaken following a range of developments impacting on the SA network, including:
- Increased wind generation capacity in the South East of South Australia;
- Reconfiguration of the network due to the establishment of the Tungkillo 275kV switching station;
- Establishment of the South East-Mayurra / Snuggery 132kV line; and
- Review of protection limits for the network, particularly for lines in the Eastern Hills and South East.
The review found that the network in its current configuration can withstand thermal loadings and meet stability requirements following a single credible contingency event (unscheduled outage) at up to a 460 MW export level across the Heywood interconnector.
Based on the findings of this review, ElectraNet has recommended an increase in the export limit of the Heywood interconnector from 300 MW to 460 MW under system normal conditions.
AEMO has accepted this advice following the completion of protection and instrumentation works. The relevant constraint equations will be modified in AEMO’s systems to take effect from Wednesday, 10 March 2010.
Actual export capability across the Heywood interconnector is dependant on the thermal limits of transmission lines and transformers, generation levels and system demand in the South East region of South Australia.
In practice, under normal operating conditions export from South Australia across the Heywood interconnector will be constrained below 460MW by thermal limits of the 132 kV transmission network in the South East region. ElectraNet and AEMO are investigating the economic feasibility of addressing these thermal limits as part of their recently announced SA Interconnector Feasibility Study.
Based on the current network configuration, analysis indicates that the export limit will typically be expected to range from 300 MW up to the 420MW combined export limit under system normal operating conditions. The relevant thermal limit equation is determined by AEMO, based on parameters provided by ElectraNet.
Combined Inter-Regional Export Capability
Whilst the export limit across the Heywood interconnector has been lifted, the combined South Australian Heywood and Murraylink Interconnection export capability limit remains unchanged at 420MW under system normal conditions.
Study results confirm that SA can export at combined levels beyond the current 420MW in total including Murraylink without violating system security in terms of system stability considerations. Based on these findings, ElectraNet has recommended a further increase in the combined export stability limit of 420 MW under system normal conditions.
The increase to this limit is dependent on the completion of further work by AEMO such as oscillatory stability studies in order to determine the allowance increase. Further information will be announced by AEMO in due course prior to implementation of this change.
For any queries in relation to these changes, please contact us.Network 2025 Vision
South Australia’s electricity transmission network is a strategic asset underpinning the State’s economic development and the prosperity of the South Australian community.
Its future direction should draw upon the commitment of all stakeholders to shared objectives for its management and long-term development.
Our Network 2025 Vision is provided online, please click here to download.
